VNC and SSH Port Fowarding

To run graphical applications on ARSC systems remotely, the Virtual Network Computing (VNC) application is available and provides some advantages beyond using X Windows over SSH, such as a detachable session. This article provides basic set up information required for this approach.

***Important Note: Please follow all of these steps with each new VNC session.***

Step 1: Install VNC on your local system

There are many different VNC viewer programs available with unique interfaces and features. The application installed on ARSC systems is TigerVNC.

After installing the software, make sure ports 5900 and 5901 are open to allow VNC traffic through your local firewall.

Step 2: Connect to the ARSC system and start the VNC server

Log onto the ARSC system over SSH and specify the appropriate ports for VNC client (your local system) and server (remote ARSC system) communication.

Launch a VNC server instance on the remote ARSC system. The initial vncserver instance will prompt you for a password to protect your session.

Step 3: Open VNC on your local system

Launch your VNC viewer program and connect to host "localhost" and port 5901. The example below shows how to launch the client using TigerVNC.

localsystem $ vncviewer localhost:5901

If you are using the TigerVNC GUI, enter "localhost:5901" into the "VNC server:" box then click the "Connect" button. You will then be prompted for the password created in Step 2. If your local VNC client connects successfully, you will then see your desktop on the remote pacman login node.

Your circumstances might require the use of different ports due to firewall issues or if you are running more than one VNC server session on the remote system. (Other people on the system might be running their own sessions as well and occupying the ports.) If this is the case, you may need to specify port 5902 or 5903.

To determine whether the VNC viewer has successfully connected, check the log file noted when the vncserver was started on the remote system.

After starting the server, the options exists to log out and back in again using different port forwarding parameters.

Note that some VNC viewer programs can automatically set up the SSH port forwarding through a command-line flag such as "-via" or some option in a graphical configuration menu.

Step 4: When finished, close the VNC session

To close your VNC session, view the open sessions then close the appropriate open session on the remote ARSC system.

Troubleshooting

Orphaned Session

If a previous VNC session remains open on the remote ARSC system, that old session will need to be closed prior to establishing a new connection using the same port. To identify and kill the old session first obtain the processID of the "Xnvc" process, then issue the kill command.

To change the password for vnc server, run the 'vncpasswd' command on the system hosting the vnc server. The manual page for this command is available online at http://linux.die.net/man/1/vncpasswd

More Information

Run "vncserver --help" and "man vncserver" for more information on how to use the application.

4 December 2014, Thursday 10:47

Events

ARSC Office has Relocated

As of November 3, 2014, the ARSC office has moved to the Elvey Building, suite 508, on the UAF campus. ARSC staff and User Support are available Monday through Friday 8am to 5pm in Elvey 508 . The physical address for the new location is 903 Koyukuk Drive. Phone numbers, email addresses, and all other ARSC services have remained the same. The HPC clusters and archival storage silo will remain in the Butrovich Computing Facility.

Connect with ARSC

The University of Alaska Fairbanks is an affirmative action/equal
opportunity employer and educational institution and is a part of the University
of Alaska system.
Arctic Region Supercomputing Center (ARSC) |PO Box 756020, Fairbanks, AK 99775 | voice: 907-450-8602 | fax: 907-450-8601 | Supporting high performance computational research in science and engineering with emphasis on high latitudes and the arctic.
For questions or comments regarding this website, contact info@arsc.edu